div{
    background-color: aquamarine;
}

.box-1{
    width: 100px;
}
.box-2{
    width: 100px;
    height: 100px;
    background-image: url('../imgs/img-2.jpg');
    background-repeat: no-repeat;
    background-size: contain;
}
.box-3{
    width: 100px;
    height: 100px;
    background: url('../imgs/img-3.jpg') no-repeat center center/cover;
}